This invention discloses frictional rotational energy transfer devices, such as drum-type brakes and band-type clutches, containing two concentric mating members, in which the external member may be contracted or the internal member may be expanded, by magnetic force, or both members may change, so that contact occurs between intervening friction members when the appropriate magnetic fields are established, and rotational energy may be transferred from one mating member to the other.
In the prior art magnetic shrink fits are disclosed, in which an internal mating member has an unstressed external diameter greater than the unstressed internal diameter of the external mating member, and in which the external magnetic mating member is increased and not decreased in diameter due to magnetic forces.
Magnetic brakes and clutches of the prior art use solenoids or similar devices to actuate conventional mechanical brakes and clutches.